<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<style>
    * { margin:0; padding:0; font:16px/100% Simsun; vertical-align:top; }
</style>
</head>
<body style="height:100px;">
<div id="cont" style="width:40px; background:#DDD; float:left; margin-right:5px;">
    <table id="float_cont" cellpadding="0" cellspacing="0" style="width:100%; height:100%; float:left;">
        <tr>
            <td>
                <table class="sub" cellpadding="0" cellspacing="0" style="width:90%; height:100%; background:#999;">
                    <tr>
                        <td>AAA</td>
                    </tr>
                </table>
                <table class="sub" cellpadding="0" cellspacing="0" style="width:90%; height:100%; background:#BBB;">
                    <tr>
                        <td>BBB</td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>
</div>
<div id="cont" style="width:40px; background:#DDD; float:left; margin-right:5px;">
    <div id="float_cont" style="display:table; width:100%; height:100%; float:left;">
        <div class="sub" style="display:table; width:90%; height:100%; background:#999;">AAA</div>
        <div class="sub" style="display:table; width:90%; height:100%; background:#BBB;">BBB</div>
    </div>
</div>
<div id="cont" style="width:40px; background:#DDD; float:left;">
    <div id="float_cont" style="display:block; width:100%; height:100%; float:left;">
        <div class="sub" style="display:block; width:90%; height:100%; background:#999;">AAA</div>
        <div class="sub" style="display:block; width:90%; height:100%; background:#BBB;">BBB</div>
    </div>
</div>
</body>
</html>